Towerfall Ascension is most probably one of the best local multiplayer games ever created. It's a game that makes and breaks friendships.
The movement speed is insane once you become aware of the things that are possible. Catching arrows is one skill, but catching multiple arrows will dodging through the air, ending with sticking to a wall, jumping back into the open area to shoot your opponent with of the arrows you just caught, is simply brilliant.
Sure it will take you time to truly master this game, which is best played with an USB controller by the way, but the road to perfection is simply brilliant.
Just like other competitive arena games - take Super Smash Bros as an example - there are several extra power-ups available. These will spawn at the beginning of each match. Some power ups give you special arrows (laser arrows or bomb arrows for example), others will have an environmental influence (slow motion or rising lava). These power-ups are always a great risk to get, because you have to engage, but the reward can be big of course.
On the other hand there's the tactic to avoid shooting. You start with three or two arrows and when your opponent shoot and miss, you can grab that arrow. But of course, once again, these missed arrows can also be used as a trick. Those are just two examples of how arena control can work in your advantage of disadvantage.
Really, Towerfall Ascension is brilliant and all you need is this baby, four USB controllers, three friends and some drinks for an AWESOME video game evening!